A few days ago as part of his Christmas schedule, Pope Benedict XVI visited a prison in Rome to decry overcrowding and assure the inmates that no matter what they had done, they are worthy of respect and dignity.
The Pope received a rapturous welcome from the prisoners, many of whom were visibly moved by the occasion.
This practice of visiting prisoners goes right back to the start of Christianity. It is a response to the words of Jesus to his followers: "I was naked and you clothed me, I was sick and you came to me, I was in prison and you visited me."
Prior to Christianity, there was no tradition in the West of seeing prisoners as people deserving of respect and dignity, as people we should be willing to visit even if they are total strangers who may have done terrible things.
This is only one of many ways in which Christianity transformed the western moral imagination, a transformation many of us now take for granted.
Christianity essentially extended Jewish morality to non-Jews, with a few touches of its own.
In antiquity, philosophy and religion operated in two completely different spheres, but Christianity merged Judaism with Greek philosophy and some of the best aspects of Roman law developing a new synthesis of its own. This synthesis built Western civilisation.
The moral sensibility found in the words of Jesus quoted above was completely unknown in the world of the Roman Empire outside of its Jewish communities.
The Christian communities made provision for their widows, who were often the most disadvantaged people in all of society. More generally, a tradition of charitable giving developed.
Slaves were permitted to become priests, something that was extremely radical at the time.
And while slavery as an institution was abolished nowhere in the world for many more centuries, as Christianity influenced Roman law, the condition of slaves was improved.
For example, emancipation became easier and it became illegal to separate married slaves by selling them to different masters.
Christianity was particularly attractive to women, something noted by pagan writers at the time who regarded it as a mark against the new religion.
Thanks to Christianity, Roman divorce laws were reformed so that men could not simply divorce their wives for no reason and throw them out on the streets.
The practice of exposing unwanted infants came to an end.
In addition, Christianity helped to develop in us the notion of individual responsibility by teaching us that we are all individually accountable before God for our actions, and king and peasant are judged equally and alike.
Christianity taught us that history has a direction, that it is moving towards the Kingdom of Heaven, a notion borrowed by all progressive ideologies that try to build Heaven on Earth, including, with disastrous effect, communism, which is essentially a Christian heresy.
Christianity even helped lay the foundations of modern science, contrary to popular belief. As Alfred North Whitehead, one of the great philosophers and mathematicians of the first half of the last century explained, the Middle Ages was "one long training in the intellect... in the sense of order".
From this, he said, came science, which was "an unconscious derivative from medieval theology".
Even our view that the State has natural limits is derived to a large extent from Christianity which established the principle that not everything belongs to Caesar, that some things belong to God. Equally, this placed limits on the power of the church itself.
Christianity also gave us the first universal creed, that is, a creed for everyone, hence the name of the Catholic Church, 'Catholic' meaning 'universal'.
Christianity told us to love our neighbour and by our neighbour was meant everyone. Before that our obligations -- such as they were -- didn't extend beyond our families or our clan or our tribe.
All universal creeds since then, including socialism, build on the sense of universal obligation given to us by Christianity.
The welfare state, for all its present faults, arises out of this sense of obligation, and from the Christian obligation to feed the hungry, clothe the naked, to look after the sick.
In his most recent book, 'Civilisation: The West and the Rest', historian Niall Ferguson quotes a member of the Chinese Academy of Social Sciences who is adamant that the political and economic success of the West is down to Christianity.
Of course, the moral transformation begun by Christianity has not been completed and never will be, and Christians themselves have often acted in ways that were, and are, de facto anti-Christ.
But so profound has the influence of Christianity been on western culture, that the West would not be the West without it.
This long process of moral transformation began at the first Christmas, 2,000 years ago. As we celebrate Christmas this year, we would do well to remember our debt to Christianity. It is far greater than we think.